90K (MAC-2 BP) GENE-EXPRESSION IN BREAST-CANCER AND EVIDENCE FOR THE PRODUCTION OF 90K BY PERIPHERAL-BLOOD MONONUCLEAR-CELLS

The tumor-derived antigen 90K (Mac-2 BP) is a widely expressed, secret ed glycoprotein found in the serum of healthy individuals and at eleva ted levels in the serum of patients with breast cancer and other types of cancer, The precise function of 90K, particularly in the context o f tumor-host relationships, has not yet been established, In this stud y, the clinical significance of 90K mRNA expression was studied in rel ation to other established prognostic parameters in 86 patients with p rimary breast carcinoma, The 2.2-kb 90K message was detected in all tu mor samples, but there was marked variation in expression levels from tumor to tumor, Patients were classified into 2 groups on the basis of 90K expression: group 1 (n = 62) included patients with low expressio n, and group 2 (n = 24) consisted of patients with high expression, An inverse significant correlation was found between the levels of 90K m RNA expression and overexpression of c-erbB2/Neu receptor kinase, a ma rker of poor prognosis for patients with breast cancer, There was no s ignificant difference between the groups with respect to tumor size, n umber of involved axillary lymph nodes, hormone-receptor status, p53 e xpression or proliferation activity as estimated by Ki-67 count, Simil arly, no association was found between the level of 90K expression and the risk of death from breast cancer, These data are at variance with published findings showing that high serum 90K levels are associated with poor survival, Significantly, investigation of 90K-gene expressio n in peripheral-blood mononuclear cells (PBMC) revealed higher levels of 90K message in PBMC of breast-cancer patients than in healthy indiv iduals, This new finding suggests that PBMC activated in response to t umor growth and progression may be an important source of serum 90K in breast cancer. (C) 1998 Wiley-Liss, Inc.